Clinical and genetic findings of incidental serous tubal intraepithelial carcinoma (145)

Abstract

<b>Objectives:</b> Serous tubal intraepithelial carcinoma (STIC) is thought to represent the precursor lesion to the high-grade serous fallopian tube or ovarian carcinoma. STIC lesions are found 0.6-6% of the time in women undergoing risk-reducing salpingo-oophorectomy (RRSO) in the setting of a known hereditary predisposition. = However, due to the rarity of incidentally identified STIC lesions, there is limited data to guide management. NCCN guidelines suggest consideration of surgical staging and referral for genetic evaluation. In the absence of a known pathogenic variant as the indication for surgery, there is no data on rates of genetic testing or long-term outcomes. The objective of this study was to describe both clinical outcomes as well as genetic information collected for patients with incidentally noted STIC lesions. <b>Methods:</b> Following IRB approval, pathology records were used to identify all patients diagnosed with a STIC lesion on final pathology from 2007-2021 at a single institution. STIC lesions were characterized utilizing immunohistochemistry. Only patients with STIC lesions undergoing surgery for benign indications were included. Demographic, clinical-pathologic, and genetic data were collected. <b>Results:</b> A total of 16 patients were identified. The median age at diagnosis was 65.5 years (39-80). Fifteen patients (93.8%) had unilateral STIC lesions with one patient having bilateral STIC lesions. Most lesions were positive for p53 (94.1%) and had increased Ki67 proliferation, defined as >10% (94.1%). Two patients (12.5%) had a personal history of malignancy prior to their STIC lesion diagnosis. Patients had a wide variety of presentations, including pelvic mass (37.5%), prolapse (31.3%), abnormal uterine bleeding (25%), and pelvic pain (6.3%). Nine patients had additional surgical procedures performed (56.3%), and no cancer diagnosis was identified for any patient. Additional procedures included contralateral salpingo-oophorectomy, omentectomy, pelvic and paraaortic lymph node dissection, and peritoneal biopsies. No patients received adjuvant treatment. Eleven patients were offered a genetic counseling referral (68.8%), with seven patients completing a counseling appointment (63.6%). Five of the seven patients who completed their visit met criteria for testing based on additional personal and/or family history (71.4%), with one patient testing positive for a PALB2 pathogenic variant (20% of tested patients). Three patients, none of whom underwent genetic testing, were subsequently diagnosed with breast cancer during the follow-up period. <b>Conclusions:</b> Incidental STIC lesions are rare. In this cohort, there were no ovarian, fallopian tube, or primary peritoneal cancer diagnoses after additional surgical staging or during follow-up. More data is needed to guide treatment recommendations. However, compared to STIC lesions in patients undergoing RRSO for a known predisposition, it is not clear whether additional surgical procedures are warranted in patients with incidentally noted STIC lesions. Our data support NCCN recommendations for referral for genetic evaluation as 71% qualified for testing. One patient (20% of those who qualified for testing) had a clinically actionable pathogenic variant. Notably, three patients later developed breast cancer; however, without genetic testing, we cannot determine if there may be a genetic link. Further studies of these lesions are warranted.